108 lines
3.5 KiB
JavaScript
108 lines
3.5 KiB
JavaScript
'use strict';
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var constants = require('./constants');
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var CrcStream = require('./crc');
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var bitPacker = require('./bitpacker');
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var filter = require('./filter-pack');
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var zlib = require('zlib');
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var Packer = module.exports = function(options) {
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this._options = options;
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options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
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options.deflateLevel = options.deflateLevel != null ? options.deflateLevel : 9;
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options.deflateStrategy = options.deflateStrategy != null ? options.deflateStrategy : 3;
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options.inputHasAlpha = options.inputHasAlpha != null ? options.inputHasAlpha : true;
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options.deflateFactory = options.deflateFactory || zlib.createDeflate;
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options.bitDepth = options.bitDepth || 8;
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// This is outputColorType
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options.colorType = (typeof options.colorType === 'number') ? options.colorType : constants.COLORTYPE_COLOR_ALPHA;
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options.inputColorType = (typeof options.inputColorType === 'number') ? options.inputColorType : constants.COLORTYPE_COLOR_ALPHA;
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if ([
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constants.COLORTYPE_GRAYSCALE,
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constants.COLORTYPE_COLOR,
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constants.COLORTYPE_COLOR_ALPHA,
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constants.COLORTYPE_ALPHA
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].indexOf(options.colorType) === -1) {
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throw new Error('option color type:' + options.colorType + ' is not supported at present');
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}
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if ([
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constants.COLORTYPE_GRAYSCALE,
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constants.COLORTYPE_COLOR,
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constants.COLORTYPE_COLOR_ALPHA,
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constants.COLORTYPE_ALPHA
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].indexOf(options.inputColorType) === -1) {
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throw new Error('option input color type:' + options.inputColorType + ' is not supported at present');
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}
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if (options.bitDepth !== 8 && options.bitDepth !== 16) {
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throw new Error('option bit depth:' + options.bitDepth + ' is not supported at present');
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}
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};
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Packer.prototype.getDeflateOptions = function() {
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return {
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chunkSize: this._options.deflateChunkSize,
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level: this._options.deflateLevel,
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strategy: this._options.deflateStrategy
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};
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};
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Packer.prototype.createDeflate = function() {
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return this._options.deflateFactory(this.getDeflateOptions());
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};
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Packer.prototype.filterData = function(data, width, height) {
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// convert to correct format for filtering (e.g. right bpp and bit depth)
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var packedData = bitPacker(data, width, height, this._options);
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// filter pixel data
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var bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
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var filteredData = filter(packedData, width, height, this._options, bpp);
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return filteredData;
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};
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Packer.prototype._packChunk = function(type, data) {
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var len = (data ? data.length : 0);
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var buf = new Buffer(len + 12);
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buf.writeUInt32BE(len, 0);
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buf.writeUInt32BE(type, 4);
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if (data) {
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data.copy(buf, 8);
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}
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buf.writeInt32BE(CrcStream.crc32(buf.slice(4, buf.length - 4)), buf.length - 4);
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return buf;
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};
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Packer.prototype.packGAMA = function(gamma) {
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var buf = new Buffer(4);
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buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
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return this._packChunk(constants.TYPE_gAMA, buf);
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};
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Packer.prototype.packIHDR = function(width, height) {
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var buf = new Buffer(13);
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buf.writeUInt32BE(width, 0);
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buf.writeUInt32BE(height, 4);
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buf[8] = this._options.bitDepth; // Bit depth
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buf[9] = this._options.colorType; // colorType
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buf[10] = 0; // compression
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buf[11] = 0; // filter
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buf[12] = 0; // interlace
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return this._packChunk(constants.TYPE_IHDR, buf);
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};
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Packer.prototype.packIDAT = function(data) {
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return this._packChunk(constants.TYPE_IDAT, data);
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};
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Packer.prototype.packIEND = function() {
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return this._packChunk(constants.TYPE_IEND, null);
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};
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